1. Field
Embodiments relate to a method of acquiring an Internet protocol (IP) address, and a set-top box and a power management server performing the method, and more particularly, to a method of acquiring an IP address to reduce an amount of standby power used in a set-top box by controlling a state of the set-top box entering a standby state using a network at a remote location.
2. Description of the Related Art
A state of an Internet protocol television (IPTV) set-top box is classified into an ON state, a standby state, and an OFF state based on whether a broadcast is viewed or not. The standby state of the set-top box indicates that a display of the set-top box is turned off because the broadcast is not viewed. In the standby state, standby power of the set-top box may be more than 10 times greater than power of an image-related home appliance used in a general house.
To reduce such an excessive amount of the standby power of the set-top box, the standby state of the set-top box may be classified into an active standby state and a passive standby state. That is, the standby power of the set-top box is classified into an active standby state power consumption and a passive standby state power consumption. A maximum of 10 watts (W) may be allowable for the active standby state power consumption, and a maximum of 1 W may be allowable for the passive standby state power consumption.
Here, the active standby state power consumption is greater than the passive standby state power consumption because a background function of the set-top box, for example, a network connection, a remote control receiver, a broadcasting tuner, and a decoder, operates in an activated state although the set-top box is powered off by a manipulation of a user. That is, when the set-top box is in the active standby state, an additional amount of power may be required to maintain such an operation of the background function. Conversely, when the set-top box is in the passive standby state, only a minimum amount of power may be required because the background function of the set-top box enters an inactivated state and only an input function of a remote controller is activated.
Thus, to reduce the standby power of the set-top box more effectively, using a section of the passive standby state may be more effective than using a section of the active standby state. However, since the set-top box provides a broadcasting service, the set-top box may update, in real time, electronic program guide (EPG) information transmitted from a headend at predetermined intervals, or a firmware or client access server (CAS) message. The set-top box may perform the updating through a network connection to the headend by activating a network connection function.
Here, the set-top box may receive an IP address allocated for the network connection from a dynamic host configuration protocol (DHCP) server, and the allocated IP address may be retrieved by the DHCP server after a predetermined period of time elapses. For example, when a lease time for the IP address allocated to the set-top box by the DHCP server is 60 minutes, the set-top box may make a request of the DHCP server to ask whether the set-top box continuously uses the allocated IP address for the rest 30 minutes at a point in time when 30 minutes, or ½ of 60 minutes, elapse. When the set-top box does not receive a response to such a request, the set-top box may request a new IP address from the DHCP server again, or request a continued use of the allocated IP address from the DHCP server. Through such a process, the set-top box may continuously receive the EPG information, or the firmware or CAS message, and perform an updating process.
Thus, when the set-top box is in the active standby state, a DHCP client function may be activated due to the activation of the background function, and thus an IP address may continuously change through the network connection. An IP connection to the headend may also be enabled, and thus messages transmitted from the headend may be immediately received and processed. Conversely, when the set-top box is in the passive standby state, the DHCP client function may be inactivated due to the inactivation of the background function, and thus operations for updating an IP address may not be performed and the connection for the IP address may not be maintained.
Thus, there is a desire for a method of providing a smooth broadcasting service and also effectively reducing an amount of standby power, although a passive standby state that is recommended for reducing the standby power is applied.